/ˈnʌlɪfaɪ/
nul·lify
BrE /ˈnʌlɪfaɪ/
NAmE /ˈnʌlɪfaɪ/
(formal)
~ sth
to make sth such as an agreement or order lose its legal force
SYN invalidate
Judges were unwilling to nullify government decisions.
~ sth
to make sth lose its effect or power
SYN negate
An unhealthy diet will nullify the effects of training.